UNIT 9 THE HUMAN GENOME I HUMAN GENETICS

UNIT 9 – THE HUMAN GENOME

I. HUMAN GENETICS (pp. 311 -313) A. Human Somatic Cells body or __. diploid 2 n l ____ cells are ______ 46 chromosomes, l Each cell contains ___ 23 pairs of chromosomes. or ___ 22 are ______, – Of the pairs, ___ homologous contain the same genes in the same order, and are called ______. autosomes

A. Human Somatic Cells l The 23 rd pair of chromosomes are the ____ sex chromosomes. – – Female =___ XX Male= ___. XY

B. Human Gametes n and Gametes are _______, haploid or __, 23 chromosomes. contain ___ egg cells made l Female gametes are _____ ovaries in the ______ in the process of _____. meiosis sperm l Male gametes are ______cells made in the _____ in the process of testes meiosis _____. l

B. Human Gametes l l Egg cell can only contain an __ X chromosome Sperm cell produced has a ___% 50 chance of Y and a ___% containing a ___ chance of 50 containing an __. X – The _____ male determines the sex of the offspring.

C. Analyzing Human Chromosome Numbers Nondisjunction Abnormal numbers of gametes chromosomes in ______ result number disorders in genetic disorders called ______. nondisjunction “not coming apart” l ______, which means _______. 1.

C. Analyzing Human Chromosome Numbers A chromosome pair fails to separate anaphase so the gametes correctly in ____ produced have an abnormal ___________. number of chromosomes l Number disorders are not inherited; therefore, they cannot be predicted Punnett squares with ________. l

C. Analyzing Human Chromosome Numbers 2. l l Karyotypes – A karyotype is a photograph of ________. chromosome pairs mitosis and are Cells are stopped during _____ stained, photographed, and the photograph is enlarged.

C. Analyzing Human Chromosome Numbers The chromosomes are cut out and homologous pairs in size arranged in ______ order, with the ____ sex chromosomes making up the 23 rd pair. number disorders l Used to detect _____ gender of an and to determine the ____ unborn child. l

C. Analyzing Human Chromosome Numbers They do not detect abnormal _______; genes therefore, a normal karyotype does not normal child! guarantee a ______

II. HUMAN GENETIC DISORDERS – NUMBER DISORDERS (pp. 313 -314) A. Autosomal Number Disorders l Most are _____. lethal l The only autosomal number disorder that allows survival into adulthood is Down syndrome __________.

Is there a problem with this karotype

A. Autosomal Number Disorders Down syndrome trisomy 21 because l known as _____ there are ___ 3 chromosomes at the 21 st position, instead of ___. 2 ____ l Individuals have characteristic facial features; growth, behavior, and mental development are all affected

Autosomal Number Disorders Down syndrome There is also a higher risk of congenital heart _____ defects. l The incidence of babies with Down syndrome is much o older higher in ______ l mothers. l

Is there a problem with this karyotype?

B. Sex Chromosome Number Disorders 1. Turner Syndrome 45 XO l Called ______ l l because individuals lack _________. 2 nd sex chromosome female typically _______, inshort stature, underdeveloped sexually, sterile with a normal life ______, expectancy.

Does this individual have a number disorder?

B. Sex Chromosome Number Disorders 2. Klinefelter Syndrome 47 XXY l Called ____. l l Symptoms do not appear until ____ pubertyat which time affected _____ males show poor sexual development and infertility. testosterone Treated with _____. Normal life expectancy.

B. Pedigrees (pp. 299 -301) l A pedigree is a diagram that follows the trait through several inheritance of a single _____ generations of a family. ______ – – l squares Males are represented by ____ circles Females, by _______. Individuals with the trait are represented shaded figures. with ____

B. Pedigrees Individuals shown with unshaded figures _________. do not show the trait parents and children l Vertical lines connect _______. spouses or l Horizontal lines connect _____ siblings _____. birth order l Children are placed in _____, from left to right _____. l

l Complete pedigrees in note packet

IV. INHERITED HUMAN GENETIC DISORDERS Gene Mutations a change in the DNA sequence of the gene _______________. A. l Causes Inherited human genetic disorders

IV. INHERITED HUMAN GENETIC DISORDERS B. Types of Inherited Genetic Disorders 1. Autosomal Genetic Disorders – Gene mutation is on any chromosome other than sex chromosomes ________ 2. Sex-Linked Disorders – Mutated gene is on X chromosome. the ____

VI. GENETIC DISORDERS - AUTOSOMAL DISORDERS l l l autosomes Most genes are carried on the ______, 44 ______ chromosomes other than the sex chromosomes. autosomal Most genetic disorders are ______ disorders. These disorders affect males and females equally and are due to _____ gene mutations. ____

Autosomal disorders can be divided into three groups based on the pattern of inheritance. 1. Autosomal Recessive 2. Autosomal Co-Dominant 3. Autosomal Dominant

A. Autosomal Recessive Disorders (pp. 297) l 1. Albinism – Characterized by failure to produce pigment, _____. Affected melanin eyes _____, skin individuals lack coloration in ______, and _____. Very susceptible to ______. hair UV light Normal Symptoms appear _____; _____ life at birth expectancy

A. Autosomal Recessive Disorders 2. Cystic Fibrosis – Characterized by excess mucus production _________in _______, lungs _____system. digestive Symptoms appear just after birth and include frequent respiratory infections, poor nutrition. With treatment, patients can survive to young adulthood. Cystic fibrosis is the fatalgenetic most common _______ disorder in the ____ United States among Caucasians. l

B. Autosomal Co-Dominant Disorders (pp. 303) Sickle cell anemia is an autosomal cohemoglobin dominant disorder that affects _____ production. oxygen to Hemoglobin is the protein that binds ____ red blood cells. 1.

Sickle cell Anemia l Individuals with the normal genotype, AA, do not have the sickle cell allele and produce only normal Hemoglobin.

Sickle cell Anemia Individuals that are SS produce abnormal hemoglobin that causes the red blood cells to “sickle” when oxygen availability is decreased; – for example, in high altitudes or during periods of stress. Sickled RBCs are more fragile, easily destroyed – results in energy due to decreased _____ ATP production in lack of ____ cells, blockage of blood vessels, and severe pain. Shortened life expectancy. Most common inherited disease African ancestry. in individuals of ______

Sickle cell Anemia l Heterozygotes (AS) produce both normal and abnormal hemoglobin and are said to have ________. They do not show symptoms of sickle cell trait the disorder. In certain areas, individuals with sickle cell trait have a benefit over individuals that lack the sickle cell allele because they are resistant to malaria _______. Malaria is a serious, sometimes fatal disease spread by mosquitoes _____ that affects millions of people each year in _______. This increased Africa malarial resistance has resulted in a very high incidence of AS individuals. If two heterozygotes 25 marry and have children, they have a ___% chance of having a child with sickle cell anemia.

C. Autosomal Dominant Disorders (pp. 298) 1. Huntington’s Disease – Fatal genetic disorder in which symptoms do not show until 30 s to 40 s Characterized by _______. deterioration of _______. nervous system Dwarfism 2. Achondroplasia - ______

V. GENETIC DISORDERS - SEXLINKED DISORDERS (pp. 305 -308) A. Sex-Linked Inheritance l “Sex-linked” if it is located on a sex X or Y chromosome (______). l In humans, sex-linked genes are almost X chromosome. always located on the larger ___ Y chromosome is much smaller and carries – The __ only a few genes related to male sexual development ____________.

A. Sex-Linked Inheritance (pp. 305 -308) l l 2 X chromosomes; Females have __ one males have ____. Females will only show recessive traits located on the X homozygous recessive chromosome if they are ____________. Males will always show a recessive trait located on the one X X chromosome because he only has _____ chromosome, – genes on the X chromosome will show. so all _______ males having a much higher This results in _____ incidence of sex-linked disorders.

A. Sex-Linked Inheritance 1. Genotypes for sex-linked traits are written using the X and Y chromosomes to show path of inheritance. – – – For example, male-pattern baldness is a sex-linked recessive trait. h. If H = normal head of hair and h = baldness, h h X Y bald male = _____; bald female = _____. X X carriers for sex-linked recessive disorders. Females can be _______ it does not show A carrier has the defective allele, but _______. H h The genotype of a female carrier is ______. X X cannot be carriers for sex-linked traits because Males _______ their 2 nd sex chromosome is the naked _______! Y

2. Sex-Linked Punnett Squares In sex-linked traits, probabilities for male and female offspring must be calculated separately because traits are inherited differently ________. If a man with a full head of hair marries a woman who is heterozygous, what is the probability they would have a son who would go bald? A daughter?

Sex-Linked Punnett Squares. If a man with a full head of hair marries a woman who is heterozygous, what is the probability they would have a son who would go bald? A daughter? Key: _________ Cross: _________ l Probability of bald daughter = ____ Probability of bald son= ______

B. Sex-Linked Disorders All of these disorders are sex-linked recessive __________. 1. Color Blindness – Inability to differentiate and distinguish colors __________.

Results For Ishihara Test(above) Normal Color Vision Red-Green Color Blind Left Right Spots Top 25 29 Top 25 Middle 45 56 Middle Spots 56 Bottom 6 8 Bottom Spots

B. Sex-Linked Disorders 2. Hemophilia – Missing an enzyme required clotting - results in for normal blood ______ uncontrolled bleeding Treated with ___________. blood transfusions, injections of missing factor.

B. Sex-Linked Disorders 3. Duchenne’s Muscular Dystrophy – Symptoms develop at ______. 3 -6 years Muscles weaken, break down __________, leading to eventual death. No available treatment or ______. cure _____ Death usually occurs before adulthood.

Examples: A colorblind female marries a man with normal vision. What is the probability of colorblind children? Key: _______ Cross: _______ 1. Probability of colorblind daughter: _______ Probability of colorblind son: ____

2. A genetics counselor interviews a couple with a family history of hemophilia to evaluate the possibility of offspring with the disorder. The woman does not have hemophilia, but states that her father had the disorder. The man is normal. Key: _______ Cross: ______ Son with: _____ daughter with: ______

III. ANALYSIS OF HUMAN INHERITANCE A. Punnett Squares & Multiple Alleles (pp. 304) more than 2 1. multiple alleles; that is, ______ alleles. An example of this is ABO blood groups. 3 alleles for this gene. Two of the There are ____ alleles, A _______ and B are co-dominant, meaning they always show if present. The third allele, _______ i____, (o) is recessive, meaning it will only show if the genotype is ___. ii –

. Punnett Squares & Multiple Alleles l 2 alleles for Each individual inherits ___ this gene, one from _____ mom and one dad from ____.

Punnett Squares & Multiple Alleles The possibilities for blood group genotypes and phenotypes are: Phenotypes Genotypes A A A I I or I i Type A blood _______ B B B Type B blood _______ I I or I i A B I I Type AB blood _______ ii Type O blood _______

l Complete ABO Blood Type Punnetts in Notes packet